It is viewed as desirable to simultaneously fertilize seed as it is planted. The preferred positioning of the fertilizer is below and to the side of the seed; an operation called "side banding".
A number of apparatus have been developed for seeding and fertilizing agricultural crops. An example of such an apparatus is U.S. Pat. No. 4,638,748 which issued to Kopecky in 1987. The Kopecky reference discloses a single furrow opening shank which has seed outlets and fertilizer outlets which are spaced.
It is generally considered desirable to plant seeds on a firm seed bed of undisturbed soil. A firm seed bed is better at retaining moisture and aids germination. The Kopecky reference unavoidably disturbs the soil in the intended seed bed.